The use of precatalyzed polyepoxide compositions and their subsequent reaction with phenols is well known. See, for example, U.S. Pat. No. 3,477,990, which is directed to precatalyzed polyepoxides containing phosphonium halides as well as their reaction with phenols.
It is also known that the polyepoxide/phenolic reaction can be catalyzed by phosphines as disclosed in U.S. Pat. No. 3,547,881 and by potassium iodide as disclosed in U.S. Pat. No. 3,978,027.
It is further known from U.S. Pat. No. 4,320,222 that high temperature storage stability of such precatalyzed epoxy compositions is improved by the addition of a small amount of an alkali metal halide or hydroxide to the compositions of U.S. Pat. No. 3,477,990.
In general, the catalysts employed in the prior art compositions noted above are quite suitable for conventional epoxy resins, i.e., glycidyl ethers of bisphenols. However, the use of such catalysts such as the phosphonium halides of U.S. Pat No. 3,477,990 do not impart sufficient storage stability to the saturated epoxy resins, particularly at elevated temperature.
Accordingly, it has now been found that saturated epoxy resins can be precatalyzed and yet be storage stable, by the addition of an ammonium salt, particularly an ammonium halide.